Quote:
Originally Posted by MetroMPG
Colour me surprised. I heard back from the company whose "documented tests" I referred to in post 14. The results were posted on the vendor's site after all. (In my defense, it would have been useful if the page I originally found that mentioned the tests had a hyperlink to the relevant page!)
Have a read - their experiment is documented here. Their test methodology beats the heck out of Pop Mech's. But it still could have been improved - easily.
They did A-B testing of a cab-high cap vs. open bed on a 2004 Dodge Ram 1500 SLT Quad Cab with a 5.7L Hemi V8. They used a closed course, and cruise control at 45 mph for 50 miles of each condition.
Here's an example of their cab-high cap:
Their claims:
19.38 mpg (US) - cap on
18.06 mpg (US) - cap off
... suggesting a 7.3% increase in MPG with the cap.
(They also document testing two tonneaus on two other trucks.)
The two most obvious pitfalls to their testing were:
1) it wasn't A-B-A, and,
2) they relied on the AAA's official "3-click" method of filling of the tank to determine fuel use (I don't care whose filling methods they were following to the letter, that approach still opens things up to potentially significant errors).
EDIT: the other important omission from the test is that it doesn't say whether the cap is better or worse than a tonneau. |
To completely fill my father's Diesel Olds and Caddies,it could take up to 10-minutes and 100-clicks before the fuel would stand steady below the detente in the filler neck.( Really a -itch on a cold windy day in West Texas!).
I give the thumbs down to AAA 3-click.